What’s the biggest online shopping day in the world? Not Valentine’s Day. Not Cyber Monday or Black Friday. They are the days that follow Thanksgiving in the U.S. and usher in the start of the holiday shopping season.

The winner is China’s Singles’ Day, celebrated November 11, or 11.11. Singles’ Day began as a day for unmarried or uncoupled people to celebrate their lives. Single students, looking for an excuse to buy themselves presents, started it on November 11, 1993, reported The Guardian.

It is symbolized by the four number ones in the date of November 11. 11 11 and is also called Double Eleven, in reference to the day it was started, said the BBC. It became a major shopping day in 2009. The CEO of an online shopping site -- Alibaba -- sought to increase sales at the e-commerce company. The CEO, Daniel Zhang, launched an annual online sale that day, said Fortune.